Marc-Andre Lemburg notes about statparse():

"""
The message ID is returned lowercased and there is no way to access
the original ID the server sent. Now at least some news servers
are very picky about the case of the ID and return errors when
fetching articles with mixed case given a lowercased version
of the ID.

The solution is simple: remove the string.lower() call.
"""

(I might add that the lowercasing was probably introduced as a result
of sloppy copy-and-paste coding; there's a string.lower in a similar
piece of code a bit higher in the source, that makes more sense --
it's lowercasing the group name.)

Lib/nntplib.py

@@ -239,7 +239,7 @@ class NNTP:
 		if n > 1:
 			nr = words[1]
 			if n > 2:
-				id = string.lower(words[2])
+				id = words[2]
 		return resp, nr, id
 
 	# Internal: process a STAT, NEXT or LAST command